Figure 1. Field efficacy and selectivity observed for six insecticides for aphid control.

A) Observed efficacy. Aphid count data were Henderson-Tilton adjusted [32] and subjected to a mixed model ANOVA by post-treatment sampling period with year of experiment, block, pass of tractor, site, and interaction terms between block and pass, block and site, and pass and site incorporated into the model. b) Observed selectivity. Field selectivity was determined using the natural enemy-to-aphid ratio in treatment plots, for exact calculation see Materials and Methods. Observed efficacy and selectivity within sampling period marked by the same letter are not significantly different at α = 0.05 (LSD).